1. Field of the Invention
This invention relates to the field of treating methods and devices for conveyor belts which are used to transport pulverulent material, such as coal or mineral ores, and in particular for treating these conveyor belts to overcome icing under temperatures below freezing as occur during mining and crushing operations during winter weather.
This invention is in the field of treating folding belt conveyors for heating hinge portions of the conveyor belts.
This invention is also in the field of controls for conveyor belts for treating or cleaning devices which coordinate the treatment of the conveyor belt, with the action of the belt treating device, so that a stoppage of the conveyor belt will immediately stop the treatment by the treating device.
2. Description of the Prior Art
It has been proposed in the prior art to clean moving conveyor belts by using steam to dislodge and remove unwanted material, as exemplified in U.S. Pat. No. 1,235,027. Another example of cleaning moving conveyor belts is U.S. Pat. No. 1,793,246 where sticky materials are cleaned from a belt used to convey wet coal.
Vibrators have been used to vibrate the belt and thereby dislodge unwanted material from the belt as illustrated in U.S. Pat. No. 2,873,847.
Proposals have been made to clean dust from conveyor belts used for conveying coal. These proposals include adding liquid treating agents, such as a silicone emulsion from a supply device, as shown in U.S. Pat. No. 4,149,624. Other liquid treating agents have been used such as illustrated in U.S. Pat. No. 4,172,811 and U.S. Pat. No. 4,197,937.
Such proposals are difficult to carry out with flat belts or with configured belts such as trough belts or folding belts of the type shown in U.S. Pat. No. 4,708,906, and U.S. Pat. No. 4,760,913.
U.S. Pat. No. 4,243,136 dicloses treatment of the surface of a coal conveyor belt with an antifreeze solution to prevent icing at locations where the winter temperatures are below freezing. This is similar to the teachings of U.S. Pat. Nos. 4,149,624; 4,172,811; and 4,197,937. U.S. Pat. No. 4,243,136 also provides a temperature sensing electrical circuit which includes a timer and which closes a normally open relay switch when the temperature falls below freezing, 32.degree. F. A coil is energized when the thermostat closes and starts a pump to pump the liquid to a nozzle and to spray antifreeze liquid solution on the conveyor belt and thereby prevent ice from forming on the belt. As long as the thermostat remains closed and the timer operates, the pump will operate. Vibrators have been used to vibrate a belt and thereby dislodge unwanted material from the conveyor belt as illustrated in U.S. Pat. No. 2,873,847.